A number of procedures performed in clinical microbiology laboratories involve repetitive, sequential, labour-intensive tasks utilizing trained technical personnel. For example, the personnel may be required to transfer samples between different pieces of equipment; they may have to simultaneously inoculate multiple bacterial cultures onto a sequential series of media; they may have to serially dilute various reagents; they may have to stain and destain bacterial specimens with several dyes; or they may have to dispense microbiological media into petri dishes. Although some of these procedures, such as media dispensation and serial dilution, have been automated, others including antimicrobial susceptibility testing by agar dilution have not. Examples of single-task automated systems usable in a clinical microbiology laboratory are found in U.S. Pat. Nos. 4,142,863; 4,166,094; 4,259,289; 4,269,803; 4,301,116; and 4,322,216.